Flexible Protocol Reconfiguration for Emergency Communication Systems

The necessity for services of emergency communication systems to be uninterrupted and reliable has brought forward strict requirements for express software upgrades of base stations. Based on reconfigurability technology, this paper presents a protocol reconfiguration scheme for emergency communication base stations. By introducing the concept of ‘local safe state,’ the proposed scheme could make the updating and replacement of the protocol software flexible and maintain interactions during the updating procedure to achieve seamless system upgrades. Further, taking TETRA protocol stack and VxWorks operating system as an example, specific processes and realization methods of reconfiguration are proposed in this paper, along with the measurements of the factors impacting on the system performance. Simulation results show that, compared with traditional technology, the method proposed significantly improves the system efficiency and does not interrupt system services.     

Genetic simulated annealing‐based coverage‐enhancing algorithm for multimedia directional sensor networks

Multimedia directional sensor network is one kind of directional sensing systems, whose coverage scheme is quite different from the omnidirectional sensing system. And it is often used in atrocious environmental surveillance, such as nuclear contaminative areas, where people can hardly arrive. In this paper, a genetic simulated annealing‐based coverage‐enhancing algorithm (GSACEA) is proposed as a coverage‐enhancing method in multimedia directional sensor networks. Firstly, GSACEA combines the genetic algorithm and simulated annealing algorithm into an algorithm with new architecture. Then, the proposed GSACEA is applied for the purpose of coverage‐enhancing in the case of directional sensor networks with rotational direction‐adjustable model. Finally, after series actions of genetic simulated annealing, the proposed method can find the approximate solution to the best area coverage rate. And according to the results of simulations, which compared the proposed method with several other classic coverage‐enhancing methods in directional sensor networks, it could be concluded that GSACEA can achieve the highest area coverage rate of directional sensor networks and reduce the iterative computing times simultaneously. Copyright © 2014 John Wiley & Sons, Ltd.     

Cost-optimal condition-monitoring for predictive maintenance of2-phase systems

The deterioration processes of many industrial systems can be modeled in 2-phases. A 2-phase system begins its life in a new condition where it resides for a random amount of time before progressing to a worn condition where it resides for a random amount of time preceding system failure. If monitoring takes place while the system is in the worn condition, preventive maintenance is performed. This paper analyzes predictive maintenance policies for systems exhibiting 2-phase behavior, and presents cost-minimizing policies, as well as satisfying policies, to determine when monitoring should take place, and for allocating monitoring resources to multiple systems. The solution approach is based on decomposing the expected cost (per unit time) into 2 components: the expected cost due to maintenance actions, and the expected cost due to monitoring actions. This decomposition facilitates the construction of operating-characteristic curves that represent policy performance, and allows evaluation of the policy tradeoffs in many situations including those with constrained or unconstrained monitoring resources, multiple or single systems, and fixed or nonfixed monitoring intervals     

Probability of error and outage in a Rice-lognormal channel forterrestrial and satellite personal communications

This letter addresses performance evaluation in a nonselective fading channel modeled by a combination of Rice and lognormal (RLN) statistics. The RLN model is valid under widely different environmental conditions, both for terrestrial cellular and for satellite personal communication systems. The letter provides semianalytical expressions for the average error probability in the RLN channel for coherent M-ary phase shift keying (PSK) and noncoherent M-ary orthogonal transmissions, then it highlights the relationship between outage probability and cell coverage for macro and microcellular systems, and finally it provides some error probability results for nongeostationary (non-GEO) satellite systems     

Identifikation kontinuierlicher Systeme mit Hilfe zeitdiskreter Modelle

Most linear processes can be modeled as discrete time linear systems. A lot of well known methods have been established to identify such systems providing time discrete transfer functions. To find a continuous model is a much more complicated task. Discrete methods for identification allow very flexible pertubation signals. Therefore it will be shown how to determine continuous transfer functions out of discrete models by assuming different envelopes of the pertubation signal. The presented algorithm is implemented in the ANA 2.5 CAE software.     

基于认知协同的时频序列设计

为了提高认知的跳频CDMA通信系统的抗干扰性能和系统容量,论文提出了一种基于认知协同的可重新配置的三无碰撞区时频序列的构造方法,并进一步证明了构造方法的有效性,列举了构造示例和汉明相关函数的性能。这种可重新配置的时频序列构造方法可以应用到认知的、可重构通信系统中。     

Filament diffusion model for simulating reset and retention processes in RRAM

Resistive switching memory (RRAM) devices are attracting an increasing interest as a possible future technology for ultra-scaled, high-density nonvolatile/dynamic memory. Although the RRAM concept is promising from the integration and scaling viewpoints, the switching mechanism and its controllability are still under debate. This paper addresses the modeling of reset and retention processes in unipolar resistive-switching memory devices. Reset transition and data loss are described in terms of the dissolution of a conductive filament, which is modeled by thermally-activated diffusion of defects/dopants. Carrier transport, Joule heating and diffusion of oxygen ions/vacancies during the electrical pulse and/or the annealing are modeled within a 3D numerical solver. The model can account for the observed dependence of reset voltage on the width of the applied triangular pulse and on the initial resistance for NiO-based RRAM devices. Retention simulations as a function of annealing temperature also agree with available data. The model provides a first example of device simulation tool for the design and the exploration of scaling and performance of RRAM cells.     

Traffic adaptive WDM networks: a study of reconfiguration issues

This paper studies the issues arising in the reconfiguration phase of broadcast optical networks. Although the ability to dynamically optimize the network under changing traffic conditions has been recognized as one of the key features of multi-wavelength optical networks, this is the first in-depth study of the tradeoffs involved in carrying out the reconfiguration process. We develop and compare reconfiguration policies to determine when to reconfigure the network, and we present an approach to carry out the network transition by describing a class of strategies that determine how to retune the optical transceivers. We identify the degree of load balancing and the number of retunings as two important, albeit conflicting, objectives in the design of reconfiguration policies, naturally leading to a formulation of the problem as a Markovian decision process. Consequently, we develop a systematic and flexible framework in which to view and contrast reconfiguration policies. We show how an appropriate selection of reward and cost functions can be used to achieve the desired balance among various performance criteria of interest. We conduct a comprehensive evaluation of reconfiguration policies and retuning strategies and demonstrate the benefits of reconfiguration through both analytical and simulation results. The result of our work is a set of practical techniques for managing the network transition phase that can be directly applied to networks of large size. Although our work is in the context of broadcast networks, the results can be applied to any wavelength-division multiplexing network where it is necessary to multiplex traffic from a large user population into a number of wavelengths     

Advanced reconfiguration framework based on game theoretical techniques in autonomic communication systems

The Autonomic Communications concept forms one promising solution to accommodate the increased complexity of legacy and emerging systems, fostering the automation and minimizing the need for human intervention. This notion implies the introduction of advanced mechanisms for autonomic decision making and self-configuration. The focus of this work is on the introduction of an advanced reconfiguration framework for the support of the following functionalities: i) efficient strategies of terminal attachment to heterogeneous wireless systems are proposed dependent on the evaluation of input stimuli from the surrounding telecom environment. ii) it is shown how to enable optimized selection and attribution of resources, iii) the application of new device configuration is examined, proposing a framework for dynamic protocol stack adaptation. It is indeed necessary to introduce a framework that will enable, policy based reconfiguration decisions supporting dynamic and optimal discovery, download and replacement of necessary protocol functionality. In this context, legacy management and control mechanisms should be enriched with such features operating in either terminal or network equipment. Namely, this contribution discusses cognitive reconfiguration management issues by introducing two basic reconfiguration units encapsulated in a unified management and control architecture: i) the component based protocol stack reconfiguration framework and ii) the resource usage optimization unit. Simulation and performance results presented in the paper prove the technical feasibility of the proposed mechanisms as well as the optimization of reconfiguration actions.     

Quality-of-Service Analysis for Statistical Multiplexing with Gaussian Distributed and Autoregressive Input

We investigate multiplexers in telecommunication systems with a workload process developing equivalent to that of a service system with semi-Markovian input, which includes fluid flow and time slotted systems. Discrete time methods are used to analyze their waiting time and loss rate.Our focus is on the performance evaluation of statistical multiplexing. Traffic flows are modeled by autoregressive processes producing autocorrelated and Gaussian distributed workload increases. The superposition of on-off voice sources approaches autoregressive processes and they also serve as a basic model for video traffic in an appropriate time scale, although video reveals a more complex autocorrelation structure. Performance results are obtained depending on only two parameters, which allow for clear conclusions about the statistical multiplexing gain with regard to bounds on loss rates as demanded in quality-of-service guarantees.     

Hardcopy image barcodes via block-error diffusion.

Error diffusion halftoning is a popular method of producing frequency modulated (FM) halftones for printing and display. FM halftoning fixes the dot size (e.g., to one pixel in conventional error diffusion) and varies the dot frequency according to the intensity of the original grayscale image. We generalize error diffusion to produce FM halftones with user-controlled dot size and shape by using block quantization and block filtering. As a key application, we show how block-error diffusion may be applied to embed information in hardcopy using dot shape modulation. We enable the encoding and subsequent decoding of information embedded in the hardcopy version of continuous-tone base images. The encoding-decoding process is modeled by robust data transmission through a noisy print-scan channel that is explicitly modeled. We refer to the encoded printed version as an image barcode due to its high information capacity that differentiates it from common hardcopy watermarks. The encoding/halftoning strategy is based on a modified version of block-error diffusion. Encoder stability, image quality versus information capacity tradeoffs, and decoding issues with and without explicit knowledge of the base image are discussed.     

Dynamic reconfiguration policies for reconfigurable coded-WDM PONs

This article studies the issues arising when reconfiguring coded-WDM networks to provide protection against eavesdropping. Although the ability to reconfigure coded-WDM PONs dynamically has been recognized as an effective means of improving the security of OCDMA networks, this article provides the first in-depth study of the tradeoffs involved in carrying out this reconfiguration process. The article commences by showing that the degree of confidentiality and the traffic loss are two important, but conflicting, objectives in the design of reconfiguration policies. The reconfiguration problem is then formulated as a Markovian decision process (MDP). The results obtained from MDP theory are applied to establish optimal reconfiguration policies for coded-WDM networks with various system parameters. Finally, the advantages of the optimal reconfiguration policies over a class of threshold-based policies are illustrated through simulation results.     

FPGA局部动态可重配置的研究

FPGA的局部动态重配置,是FPGA配置方法一个革新性进步,具有广阔的应用前景.相应地,FPGA结构、设计流程以及解决方案都会发生很大的变化.文中时可局部动态重配置的FPGA进行结构剖析,并提出进行局部动态重配置的方法以及应用的解决方案.     

Convoy Tree Based Fuzzy Target Tracking in Wireless Sensor Network

One important application area of wireless sensor network (WSN) is tracking mobile target. When a target enters in a monitoring region and moves around it, the deployed WSN is used to collect information about the target and send it to the nearby base station. In this paper, we propose a fuzzy based target tracking algorithm (CTFTT). The algorithm constructs a convoy tree around the target and dynamically moves the tree along with the target by adding new nodes into the tree and removing old nodes from the tree. The expansion, contraction and reconfiguration of the tree is done using a fuzzy based sensing model. Important advantages are (1) convoy tree provides 100% coverage, (2) fuzzy mechanism helps to localize the evevts such as tree expansion, contraction and reconfiguration. This in turn helps to reduce the energy consumption in the network. Localized events also reduce communication overhead. Thus CTFTT is able to support the tracking of even fast moving objects. Extensive simulation shows that our algorithm performs better than the existing tree based algorithms in terms of coverage and energy.     

A cognitive model‐based approach for autonomic fault management in OpenFlow networks

Autonomic network management is an approach to the management of complex networks and services that incorporates the detection, diagnosis and reconfiguration, as well as optimization, of their performance. A control loop is fundamental as it facilitates the capture of the current state of the networks and the reconfiguration of network elements without human intervention. For new networking architectures such as software‐defined networking and OpenFlow networks, in which the control plane is moved onto a centralized controller, an efficient control loop and decision making are more crucial. In this paper, we propose a cognitive control loop based on a cognitive model for efficient problem resolving and accurate decision making. In contrast to existing control loops, the proposed control loop provides reactive, deliberative and reflective loops for managing systems based on analysis of current status. In order to validate the proposed control loop, we applied it to fault management in OpenFlow networks and found that the protection mechanism provides fast recovery from single failures in OpenFlow networks, but it cannot cover multiple‐failure cases. We therefore also propose a fast flow setup (FFS) algorithm for our control loop to manage multiple‐failure scenarios. The proposed control loop adaptively uses protection and FFS based on analysis of failure situations. We evaluate the proposed control loop and the FFS algorithm by conducting failure recovery experiments and comparing its recovery time to those of existing methods. Copyright © 2013 John Wiley & Sons, Ltd.     

Atomic level modeling of boron diffusion through silicon oxide before and after plasma nitridation

Ab initio quantum chemical calculations on model systems containing one siloxane bond have been employed to get insight into the mechanisms of boron diffusion in silicon oxide and suppression of boron penetration into gate oxide by plasma-induced nitridation. Calculated energies of insertion of various dopants into siloxane bond show a certain correlation with experimental diffusion activation energies through silicon oxide. Plasma-induced nitridation leads to incorporation of nitrogen atoms into siloxane bond. Energy gain for B insertion into a nitridized siloxane bond dramatically increases compared to its insertion into a regular siloxane bond: from ≈3 eV to more than 10 eV. This might be a plausible explanation of the B diffusion retardation after plasma nitridation. Semi-empirical quantum chemical methods showed a qualitative agreement with ab initio ones for insertion energies and have been applied to larger model systems. Model calculation of the neutral N atom interaction with a siloxane bond containing the hydroxyl group suggested a possible explanation for an absence of nitridation of oxide fluxes composed only of low energy neutral N atoms.     

Modern development methods and tools for embedded reconfigurable systems: A survey

Heterogeneous reconfigurable systems provide drastically higher performance and lower power consumption than traditional CPU-centric systems. Moreover, they do it at much lower costs and shorter times to market than non-reconfigurable hardware solutions. They also provide the flexibility that is often required for the engineering of modern robust and adaptive systems. Due to their heterogeneity, flexibility and potential for highly optimized application-specific instantiation, reconfigurable systems are adequate for a very broad class of applications across different industry sectors. What prevents the reconfigurable system paradigm from a broad proliferation is the lack of adequate development methodologies and electronics design tools for this kind of systems. The ideal would be a seamless compilation of a high-level computation process specification into an optimized mixture of machine code executed on traditional CPU-centric processors and on the application-specific decentralized parallel data-flow-dominated reconfigurable processors and hardware accelerators. Although much research and development in this direction was recently performed, the adequate methodologies and tools necessary to implement this compilation process as an effective and efficient hardware/software co-synthesis flow are unfortunately not yet in place. This paper focuses on the recent developments and development trends in the design methods and synthesis tools for reconfigurable systems. Reconfigurable system synthesis performs two basic tasks: system structure construction and application process mapping on the structure. It is thus more complex than standard (multi-)processor-based system synthesis for software-programmable systems that only involves application mapping. The system structure construction may involve the macro-architecture synthesis, the micro-architecture synthesis, and the actual hardware synthesis. Also, the application process mapping can be more complicated and dynamic in reconfigurable systems. This paper reviews the recent methods and tools for the macro- and micro-architecture synthesis, and for the application mapping of reconfigurable systems. It puts much attention to the relevant and currently hot topic of (re-)configurable application-specific instruction set processors (ASIP) synthesis, and specifically, ASIP instruction set extension. It also discusses the methods and tools for reconfigurable systems involving CPU-centric processors collaborating with reconfigurable hardware sub-systems, for which the main problem is to decide which computation processes should be implemented in software and which in hardware, but the hardware/software partitioning has to account for the hardware sharing by different computation processes and for the reconfiguration processes. The reconfigurable system area is a very promising, but quite a new field, with many open research and development topics. The paper reviews some of the future trends in the reconfigurable system development methods and tools. Finally, the discussion of the paper is summarized and concluded.     

Probabilistic testing of OSI protocols

Protocols are large and complex software systems. Complete conformance testing of an implementation against its standard may not be feasible in terms of the resources available. This paper discusses a new approach, the P-method, to the testing of meaningful subsets of communication protocols for an asynchronous model of communication. The approach is based on the probabilistic verification of protocols, which is carried out on the more probable part of the protocol first. The technique can be used for generating probabilistic test sequences for the conformance testing of communication protocols to standards. The proposed method yields meaningful protocol test sequences which test the most probable behaviors of a protocol when the testing of the complete protocol is not feasible. Probabilistic test sequences can be categorized into different classes. The higher the class a probabilistic test sequence is in, the larger the extent of the protocol it covers, and the better is the fault coverage. If the class of a test sequence is high enough, its fault coverage is comparable to the fault coverage of test sequences generated by other methods. Results from a study of the P-method, using alternating bit protocol (ABP) and a subset of NBS TP4 as examples, support the claims above. It can also be shown that if errors are introduced only to the more probable part of the protocol, the fault coverage of P-method is also comparable to other methods     

Generation of design verification tests from behavioral VHDLprograms using path enumeration and constraint programming

A method for generation of design verification tests from behavior-level VHDL programs is presented. The method generates stimuli to execute desired control-flow paths in the given VHDL program. This method is based on path enumeration, constraint generation and constraint solving techniques that have been traditionally used for software testing. Behavioral VHDL programs contain multiple communicating processes, signal assignment statements, and wait statements which are not found in traditional software programming languages. Our model of constraint generation is specifically developed for VHDL programs with such constructs. Control-flow paths for which design verification tests are desired are specified through certain annotations attached to the control statements in the VHDL programs. These annotations are used to enumerate the desired paths. Each enumerated path is translated into a set of mathematical constraints corresponding to the statements in the path. Methods for generating constraint variables corresponding to various types of carriers in VHDL and for mapping various VHDL statements into mathematical relationships among these constraint variables are developed. These methods treat spatial and temporal incarnations of VHDL carriers as unique constraint variables thereby preserving the semantics of the behavioral VHDL programs. Constraints are generated in the constraint programming language CLP(R) and are solved using the CLP(R) system. A solution to the set of constraints so generated yields a design verification test sequence which can be applied for executing the corresponding control path when the design is simulated. If no solution exists, then it implies that the corresponding path can never be executed. Experimental studies pertaining to the quality of path coverage and fault coverage of the verification tests are presented